Contents

Description

The real time rendering of big 3D city models with terrain model is difficult. There are use cases for which a photo texture is not necessary. For easy rendering of big areas are scheduled small textures with 64x64 Pixel. These textures have free RGB background and one of more faces einem ("doors" and "windows" representation) with other RGB value.

The textures should be used only for building facades in a lower "level of detail" LOD 1 and 2 for 3D city models.

The low resolution texture should facilitate the real-time rendering of 3D city models.

Of course, this method of representation can not show the architectural details, but it is suitable for widespread texturing of generalized city models for online - rendering.

64x64 Raster:construction grid for a texture

This method of texturing is not for fotorealistic representation designed!

Textures of this type should only show number of floors of the buildings
and provide a rough orientation and recognition of the spatial situation.

Pros:

Easily true-time rendering of 3D cities.

Standardization of generic textures for 3D City Models

Uniform naming system of the generic texture library: The entire texture library is small

It allows faster texturing of large areas

Phototexturing vs. low resolution texturing

High resolution, unique textures or repeatable textures (Fototextur) look a lot better. Of course, this textures should gradually be used in all 3D buildings.
But you must know about the difficulties of the high resolution texturing:

High labor costs. For generating of unique textures each building must be photographed from each side. You get the best texture when you shot frontal photograph of each facade. These photos will then be processed (equalizing,matching).

Real-time visualization. The amount of data that will result from photo textures is relatively large. Either one is developed mechanisms that provide texture optimization, or the real-time rendering will be difficult.

Despite these difficulties, it is obviously that the future belongs to fototexturierung:

Shifting of the texture

The texture usually starts in the lower left corner of the surface that is textured (insertion point).
Sometimes it is advantageous if the insertion point of the texture is not at the beginning of a surface:

This texture is repeated six times along the x and 3 times along the y axis:

Result:

Texturing of surfaces with more textures

Often it is impossible to make a good surface representation with only one texture. In this case it is necessary to divide the surface in smaller areas. Each of this areas gets a separate texture.